Transmitter, receiver, and wireless communication method thereof

ABSTRACT

A transmitter is configured to transmit a radio frequency (RF) signal to a receiver. The receiver is configured to receive the RF signal and decode data. Furthermore, a method of wireless communication is provided between the transmitter and the receiver, in which the transmitter transmits to the receiver the RF signal. A carrier phase of the RF signal is randomly converted. The receiver detects an envelope of the RF signal, and extracts data from the RF signal.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit under 35 USC 119(a) of Korean PatentApplication No. 10-2013-0069157, filed on Jun. 17, 2013, in the KoreanIntellectual Property Office, the entire disclosure of which isincorporated herein by reference for all purposes.

BACKGROUND

1. Field

The following description relates to a transmitter configured totransmit a radio frequency (RF) signal, a receiver configured to receivean RF signal and decode data, the transmitter and the receiverwirelessly communicating, and a wireless communication method thereof.

2. Description of Related Art

With rapid development and commercialization of wireless networktechnology, use of sensor networks is spreading extensively, and furthergrowth looms for market latency of this technology. In general, awireless sensor device may be applied for home security, a medicalfield, mobile healthcare, chemical/biological abnormality monitoring,mechanical disorder/malfunction diagnosis, environmental monitoring,disaster related information sensing, intelligent logistics management,real-time security, and remote monitoring.

A size of sensors in various wireless sensor networks and a local areanetwork (LAN) may be small, while conditions of low power/low complexitymay need to be met for the sensors to operate for a long period of time.In particular, a wireless body area network (WBAN) installed in a bodyand in which wireless communication is performed with a mobile device oranother sensor in the body may require relatively more strict conditionsin terms of low complexity/low power. To achieve such low power/lowcomplexity conditions, an ultra low power radio frequency (RF) structuremay be needed rather than an existing high power RF structure.

A noncoherent modulation scheme, for example, noncoherent on-off keying(OOK), amplitude-shift keying (ASK), and pulse position modulation(PPM), may be deemed appropriate to be applied to a low power/lowcomplexity receiver.

SUMMARY

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

In accordance with an illustrative configuration, there is provided atransmitter including a generator configured to convert input data to apulse; a converter configured to randomly change a phase of a radiofrequency (RF) oscillating signal; and a transmitter configured toconvert the pulse to an RF signal based on the RF oscillating signal,and transmit the RF signal to a receiver.

The converter may be configured to randomly reverse a phase of the RFoscillating signal in a time interval determined based on a transmissionperiod of a transmission symbol.

The converter may be configured to randomly change a phase of the RFoscillating signal in a time interval determined based on a transmissionperiod of a transmission symbol to a predetermined value.

The converter may be configured to control an operation of an oscillatoroutputting the RF oscillating signal, and change the phase of the RFoscillating signal to a continuous phase value.

The converter may be configured to apply a function including a randomvalue in a time interval, which is based on a transmission period of atransmission symbol, to the RF oscillating signal and change the phaseof the RF oscillating signal.

The converter may be configured to determine change periods of the phasecorresponding to a positive integer multiple of a transmission period ofa transmission symbol, and randomly change the phase of the RFoscillating signal for the change periods.

The transmitter may be configured to transmit the RF signal to thereceiver to decode data based on an envelope of the received RF signal.

The transmitter may be configured to transmit the RF signal to thereceiver to decode data without using carrier phase information of theRF signal.

The generator includes a data encoder configured to map input data to anelement set; and a pulse shaper configured to generate the pulsecorresponding to the data based on a result of the mapping.

The pulse shaper may be configured to overlap pulses corresponding to adata sequence on a time axis, and convert the data sequence to a pulseseries.

The pulse shaper may be configured to adjust a shape of each pulse toavoid distortion of a transmission waveform in a limited bandwidth whiletransmitting the transmission waveform corresponding to a transmissionbit.

In accordance with another illustrative configuration, there is provideda transmitter including a data encoder configured to output a quantizedresult indicative of mapping input data to an element set; a converterconfigured to randomly change a code of the quantized result and outputan output signal indicative thereof; a pulse shaper configured toconvert the output signal to a form of a pulse; and a transmitterconfigured to convert the pulse to an RF signal based on an RFoscillating signal and transmit the RF signal to a receiver.

The converter may be configured to randomly change the code to anegative code in a time interval determined based on a transmissionperiod of a transmission symbol.

The converter may be configured to apply a function including a randomvalue in a time interval, which is based on a transmission period of atransmission symbol, to the quantized result and change the code and asize of the quantized result.

The converter may be configured to randomly change the code of thequantized result at points of time corresponding to positive integermultiples of the transmission period.

The data encoder includes an encoder configured to perform encoding byincluding an error correction code in the input data, a spreaderconfigured to apply a spreading code sequence to the encoded input data,and a symbol mapping unit configured to map a symbol with the encodedinput data to which the spreading code sequence is applied.

The transmitter may also include a mixer configured to generate the RFsignal corresponding to the input data by multiplying the RF oscillatingsignal and a pulse series of a low frequency band.

In accordance with an illustrative example, there is provided a receiverincluding an envelope detector configured to detect an envelope of aradio frequency (RF) signal; and a data decoder configured to decodedata based on the envelope of the RF signal, wherein the RF signalcomprises a randomly changed carrier phase.

The RF signal may be configured to correspond to an RF signal with acarrier phase randomly reversed in a time interval determined based on atransmission period of a transmission symbol.

The RF signal may be configured to correspond to an RF signal with acarrier phase randomly changed to a predetermined value in a timeinterval determined based on a transmission period of a transmissionsymbol.

The RF signal may be configured to correspond to an RF signal with acarrier phase randomly changed to a continuous phase value.

In accordance with an illustrative configuration, there is provided amethod of wireless communication at a transmitter, including convertinginput data to a pulse; randomly changing a phase of a radio frequency(RF) oscillating signal; converting the pulse to an RF signal based onan RF oscillating signal; and transmitting the RF signal to a receiver.

In accordance with an illustrative configuration, there is provided amethod of wireless communication, including receiving a radio frequency(RF) signal from a transmitter; detecting an envelope of the RF signal;and decoding data based on the envelope of the RF signal, wherein the RFsignal comprises a randomly changed carrier phase.

Other features and aspects will be apparent from the following detaileddescription, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects will become apparent and more readilyappreciated from the following description of the embodiments, taken inconjunction with the accompanying drawings in which:

FIG. 1 is a diagram illustrating an example of a method of wirelesscommunication between a transmitter and a receiver, in accord with anillustrative configuration.

FIG. 2 is a diagram illustrating an example of a configuration of atransmitter, in accord with an illustrative configuration.

FIG. 3 is a diagram illustrating an example of a configuration of areceiver, in accord with an illustrative configuration.

FIG. 4 is a diagram illustrating an example of an operation to transmita radio frequency (RF) signal based on a method to convert a carrierphase, in accord with an illustrative configuration.

FIG. 5 is a diagram illustrating another example of an operation totransmit an RF signal based on a method to convert a carrier phase, inaccord with an illustrative configuration.

FIG. 6 is a diagram illustrating an example of a detailed configurationof a data encoder, in accord with an illustrative configuration.

FIG. 7 is a diagram illustrating an example of an operation of thetransmitter based on a signal waveform, in accord with an illustrativeconfiguration.

FIG. 8 is a diagram illustrating another example of an operation of thetransmitter based on a signal waveform, in accord with an illustrativeconfiguration.

FIG. 9 is a diagram illustrating still another example of an operationof the transmitter based on a signal waveform.

FIG. 10 is a diagram illustrating an example of an operation to transmitan RF signal based on a method to convert a baseband signal.

FIG. 11 is a diagram illustrating an example of an operation to transmitan RF signal based on a method to convert a baseband signal.

FIG. 12 is a diagram illustrating an example of an operation of thereceiver, in accord with an illustrative configuration.

FIG. 13 is a diagram illustrating an example of a low frequency bandsignal included in an output signal of a power amplifier, in accord withan illustrative configuration.

FIG. 14 is a diagram illustrating an example of a method of wirelesscommunication between the transmitter and the receiver based on a signalwaveform, in accord with an illustrative configuration.

FIGS. 15 and 16 are graphs illustrating examples of a simulation resultof comparing efficiency of an existing method of wireless communicationand efficiency of a proposed method of wireless communication, in accordwith an illustrative configuration.

FIG. 17 is a flowchart illustrating an example of a method of wirelesscommunication performed by a transmitter, in accord with an illustrativeconfiguration.

FIG. 18 is a flowchart illustrating an example of a method of wirelesscommunication performed at a transmitter, in accord with an illustrativeconfiguration.

FIG. 19 is a flowchart illustrating an example of a method of wirelesscommunication performed at a receiver, in accord with an illustrativeconfiguration.

Throughout the drawings and the detailed description, unless otherwisedescribed, the same drawing reference numerals will be understood torefer to the same elements, features, and structures. The relative sizeand depiction of these elements may be exaggerated for clarity,illustration, and convenience.

DETAILED DESCRIPTION

The following detailed description is provided to assist the reader ingaining a comprehensive understanding of the methods, apparatuses,and/or systems described herein. Accordingly, various changes,modifications, and equivalents of the methods, apparatuses, and/orsystems described herein will be suggested to those of ordinary skill inthe art. The progression of processing steps and/or operations describedis an example; however, the sequence of and/or operations is not limitedto that set forth herein and may be changed as is known in the art, withthe exception of steps and/or operations necessarily occurring in acertain order. Also, description of well-known functions andconstructions may be omitted for increased clarity and conciseness.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the presentinvention. As used herein, the singular forms “a,” “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises” and/or “comprising,” when used in this specification,specify the presence of stated features, integers, steps, operations,elements, and/or components, but do not preclude the presence oraddition of one or more other features, integers, steps, operations,elements, components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which the present invention belongs. Itwill be further understood that terms, such as those defined in commonlyused dictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

Throughout the drawings and the detailed description, the same referencenumerals refer to the same elements. The drawings may not be to scale,and the relative size, proportions, and depiction of elements in thedrawings may be exaggerated for clarity, illustration, and convenience.

The features described herein may be embodied in different forms, andare not to be construed as being limited to the examples describedherein. Rather, the examples described herein have been provided so thatthis disclosure will be thorough and complete, and will convey the fullscope of the disclosure to one of ordinary skill in the art.

FIG. 1 illustrates an example of a method of wireless communicationbetween a transmitter 110 and a receiver 120, in accord with anillustrative configuration.

In one example, the transmitter 110 and the receiver 120 performwireless communication, based on a noncoherent modulation/demodulationscheme. The noncoherent modulation/demodulation scheme refers to ascheme in which, unlike a coherent modulation/demodulation scheme, areceiver decodes data without using carrier phase information in atransmitter. For example, the transmitter 110 and the receiver 120communicate using the noncoherent modulation/demodulation scheme, suchas noncoherent on-off keying (OOK), to determine a presence of a signalby detecting an envelope or amplitude-shift keying (ASK). Unlike thecoherent modulation/demodulation scheme, the noncoherentmodulation/demodulation scheme provides a communication environment oflow power/low complexity because elements requiring a high costsynchronization process to obtain a carrier phase value, or requiringhigh power, such as a mixer or a linear amplifier, are not used.

The transmitter 110 converts data to be transmitted to the receiver 120to a form of a radio frequency (RF) signal, and transmits the converteddata to the receiver 120. The transmitter 110 transmits data, using anRF signal of which a carrier phase is randomly changed. The transmitter110 randomly generates a carrier phase, applies the randomly generatedcarrier phase to an RF oscillating signal, for example, an output signalof an RF oscillator, and generates an RF signal of which a carrier phaseis randomly changed. In one illustrative example, the carrier phaseinformation of the RF signal bears no relevance to a transmissionsymbol, and is not transmitted to the receiver 120. Also, thetransmitter 110 converts a sign of a baseband signal differently in apredetermined time interval or an arbitrary time interval, applies theconverted code to the RF oscillating signal, and generates an RF signalin a form similar to a form of the RF signal of which the carrier phaseis randomly changed.

The receiver 120 receives an RF signal from the transmitter 110, anddecodes data from the RF signal. The receiver 120 detects an envelope ofthe RF signal, and extracts data from the RF signal based on thedetected envelope. The receiver 120 decodes data from the detection ofthe envelope, and estimates a transmission symbol without usinginformation associated with a random carrier phase used in thetransmitter 110.

The transmitter 110 transmits data through the RF signal of which thecarrier phase is randomly changed, or an RF signal in a similar form,and prevents an occurrence of a line spectrum in which power density isrelatively concentrated at a predetermined frequency. The line spectrummay occur due to power concentration through reinforcing interference ata predetermined frequency of a frequency area.

As the line spectrum is removed, a system for wireless communicationincluding the transmitter 110 and the receiver 120 effectively reducepower and absolute magnitude of power, defined in a power spectraldensity (PSD) mask of a communication protocol. In one example,conditions of power reduction may refer to a limit in magnitudereduction of power, relative to a center frequency, and in a frequencyinterval adjacent to the center frequency. The conditions of absolutemagnitude of power may also refer to conditions with an absolutemagnitude of power to be satisfied in a frequency interval adjacent tothe center frequency. Also, as the line spectrum is removed, the systemfor wireless communication may provide a power spectrum suitable forvarious transmission symbol sequence patterns, and enable the receiver120 to have a stable reception. Further, the system for wirelesscommunication may prevent performance degradation of a circuit in whichpower density is concentrated in a center frequency. When the powerdensity is concentrated at the center frequency, a direct current (DC)offset component is relatively high, and the performance of a circuitmay deteriorate because a probability of saturation may increase duringa signal amplifying process.

FIG. 2 illustrates an example of a configuration of a transmitter 210,in accordance with an illustrative configuration.

Referring to FIG. 2, the transmitter 210 includes a pulse generator 220,a carrier phase converter 250, and an RF signal transmission unit 260.The pulse generator 220 includes a data encoder 230 and a pulse shaper240.

The pulse generator 220 converts data to generate a pulse. In otherwords, the pulse generator 220 converts data to a discrete element, andgenerates a pulse corresponding to the discrete element. The pulsegenerator 220 outputs a pulse sequence in which a plurality of pulsesoverlaps. For example, when the pulse generator 220 is assumed to usethe noncoherent OOK scheme, a pulse in a predetermined shape may begenerated when a binary symbol to be transmitted is “1”. In thealternative, the pulse generator 220 may not generate a pulse when abinary symbol to be transmitted is “0”.

The data encoder 230 encodes input data or a data sequence to betransmitted in a form of a transmission bit. The data encoder 230 mapsthe input data or the data sequence to a predetermined element set. Forexample, the predetermined element set may be configured by “0” andpredetermined positive numbers greater than “0”. When the element set isconfigured to be {0, 1}, the data encoder 230 encodes input data throughmapping the input data to “0” or “1” as a binary encoder of thenoncoherent OOK scheme. The data encoder 230 maps the input data to apredetermined element set and outputs a quantized result.

In transmitting multi-bits per transmission a symbol, for example, in acase of the ASK in which 2 bits are transmitted per transmission of asymbol, the data encoder 230 groups an input data sequence into twobits, and maps the input data sequence to one of four levels “0”, “1”,“2”, and “3”.

The pulse shaper 240 generates a pulse corresponding to the input databased on a result of the mapping of the data encoder 230. The pulseshaper 240 multiplies an output value of the data encoder 230 with apredetermined pulse shape and generates a pulse corresponding to thedata input. The pulse shaper 240 overlaps pulses corresponding to thedata sequence on a time axis, and converts the data sequence to a formof a pulse series. The pulse shaper 240 adjusts a shape of a pulse toavoid distortion of a transmission waveform in a limited bandwidth whiletransmitting the transmission waveform corresponding to a predeterminedtransmission bit.

The transmitter 210 further includes a voltage-controlled oscillator(VCO) generating an RF oscillating signal. The VCO outputs the RFoscillating signal corresponding to a carrier frequency.

The carrier phase converter 250 randomly changes a phase of the RFoscillating signal. The carrier phase converter 250 generates a randomcarrier phase, applies the generated carrier phase to the RF oscillatingsignal, and randomly changes the phase of the RF oscillating signal. Thecarrier phase converter 250 applies a function having a random value ina time interval determined based on a transmission period of atransmission symbol, and changes the phase of the RF oscillating signal.In one example, a length of the time interval determined based on thetransmission period of the transmission symbol has a length being apositive integer, multiple of the transmission period of thetransmission symbol. Also, the carrier phase converter 250 changes thephase of the RF oscillating signal using various functions.

The carrier phase converter 250 shifts the phase of the RF oscillatingsignal in the time interval determined based on the transmission periodof the transmission symbol. For example, the carrier phase converter 250applies a function having a value of “+1” or “−1” in the time intervaldetermined in the transmission period of the transmission symbol, andreverses the phase of the RF oscillating signal in a time intervalrandomly determined. The carrier phase converter 250 changes the phaseof the RF oscillating signal to a predetermined value in the timeinterval determined in the transmission period of the transmissionsymbol. For example, the carrier phase converter 250 changes the phaseof the RF oscillating signal to one of four predetermined phase values,π/4, 3 π/4, 5 π/4, and 7π/4, using two different functions having valuesof “+1/√{square root over (2)}” or “−1/√{square root over (2)}” in thetime interval determined in the transmission period of the transmissionsymbol.

The carrier phase converter 250 controls an operation of an oscillatorto output the RF oscillating signal, and randomly changes the phase ofthe RF oscillating signal to a continuous phase value. In one example,the carrier phase converter 250 changes the phase of the RF oscillatingsignal to a predetermined value in a range of “0” degree to “360”degrees for respective predetermined periods. For example, the carrierphase converter 250 turns off/turns on the VCO per predetermined period,and randomly changes the phase of the RF oscillating signal to acontinuous phase value in a range of “0” degree to “360” degrees.

The carrier phase converter 250 determines a change period of a phasecorresponding to positive integer multiples of the transmission periodof the transmission symbol, and randomly changes the phase of the RFoscillating signal per determined change period. For example, when apositive integer K=1, the carrier phase converter 250 generates a randomcarrier phase, irrespective of the transmission symbol per transmissionof the transmission symbol, and applies the generated random carrierphase to the phase of the RF oscillating signal, or a carrier.

The carrier phase converter 250 applies a random phase to the RFoscillating signal, and prevents concentration of power density fromoccurring in a predetermined frequency due to reinforcing interferenceof a frequency. Also, the carrier phase converter 250 applies a randomphase to the RF oscillating signal, and removes a DC offset component ofan RF signal to be transmitted.

The RF signal transmission unit 260 converts a pulse to an RF signalbased on an RF oscillating signal from which a phase is converted. TheRF signal transmission unit 260 includes a mixer (not shown) to multiplyan RF oscillating signal to which a random carrier phase is applied anda low frequency signal output by the pulse shaper 240. The RF signaltransmission unit 260 generates an RF signal through the mixer. Thegenerated RF signal may be wirelessly transmitted through a poweramplifier (not shown).

According to another example, the RF signal transmission unit 260generates an RF signal using the power amplifier instead of the mixer.The RF signal transmission unit 260 receives the RF oscillating signalto which the random carrier phase is applied and the low frequencysignal output from the pulse shaper 240. The RF signal transmission unit260 then applies the RF oscillating signal and the low frequency signalto the power amplifier. The RF signal transmission unit 260 generatesthe RF signal without using the mixer. In a case in which the RF signalis generated without using the mixer, the RF signal is generated usinglow power.

The receiver decodes data based on an envelope of a received RF signal.The RF signal transmission unit 260 may not need to transmit carrierphase information to the receiver because the receiver may decode datawithout using the carrier phase information of the received RF signal.For example, when a system for wireless communication between thetransmitter 210 and the receiver is assumed to be a spread spectrumsystem that multiplies a spreading code sequence when transmitting bitinformation, carrier related information generated by a transmissionsymbol may bear no relevance to the spreading code sequence, which ismutually shared between the transmitter 210 and the receiver. During aprocess in which the receiver detects an envelope, an irregular signalof the random carrier phase may disappear.

FIG. 3 illustrates an example of a configuration of a receiver 310, inaccord with an illustrative configuration.

Referring to FIG. 3, the receiver 310 includes an RF signal receptionunit 320, an envelope detector 330, and a data decoder 340.

The RF signal reception unit 320 receives the RF signal from atransmitter. The RF signal has a carrier phase randomly changed by thetransmitter. For example, the RF signal refers to an RF signal with acarrier phase randomly reversed in a time interval determined based on atransmission period of a transmission symbol, or an RF signal with acarrier phase randomly changed to a predetermined value in the timeinterval determined based on the transmission period of the transmissionsymbol. The RF signal may also refer to an RF signal with a carrierphase randomly changed to a continuous phase value.

The envelope detector 330 detects an envelope from the received RFsignal. In one example, during a process in which the envelope detector330 detects the envelope, an irregular signal of a random carrier phasedisappears.

The data decoder 340 decodes data based on the envelope of the RFsignal. For example, the data decoder 340 detects an envelope from an RFsignal, and performs sampling on an envelope pattern to convert theenvelope pattern from an analog signal to a digital signal. The datadecoder 340 extracts data using an envelope, and estimates atransmission symbol without using carrier phase information of the RFsignal.

FIG. 4 illustrates an example of an operation to transmit an RF signalbased on a method to convert a carrier phase, in accord with anillustrative configuration.

In one illustrative example, a transmitter 410 illustrated in FIG. 4corresponds to the example of the transmitter 210 of FIG. 2.Accordingly, for any descriptions omitted in FIG. 4, reference may bemade to FIG. 2.

Referring to FIG. 4, the transmitter 410 includes a data encoder 440, apulse shaper 450, a carrier phase converter 420, a VCO 430, and a poweramplifier 460.

The data encoder 440 encodes data to be transmitted in a form of atransmission bit. The data encoder 440 maps input data, or a datasequence, to a predetermined element set.

The pulse shaper 450 generates a pulse corresponding to the data inputbased on a result of the mapping performed by the data encoder 440. Thepulse shaper 450 multiplies an output value of the data encoder 440 anda predetermined pulse shape, and generates a pulse corresponding to thedata. The pulse shaper 450 overlaps pulses corresponding to a datasequence on a time axis, and converts the data sequence to a form of apulse series.

The carrier phase converter 420 generates a function to randomly changea phase of an RF oscillating signal. The carrier phase converter 420generates a random carrier phase, and provides the generated carrierphase to the VCO 430 to generate an RF oscillating signal. The carrierphase converter 420 generates at least one function having apredetermined value randomly determined, in a time interval determinedbased on the transmission period of a transmission symbol. For example,the carrier phase converter 420 generates two different functions having“+1/√{square root over (2)}” or “−1/√{square root over (2)}” in the timeinterval determined based on the transmission period of the transmissionsymbol.

The at least one function provided to the VCO 430 may be applied to theRF oscillating signal generated in the VCO 430, and the phase of the RFoscillating signal may be randomly changed. The phase of the RFoscillating signal may be randomly changed at a predetermined timeinterval and based on the function generated by the carrier phaseconverter 420.

The carrier phase converter 420 generates a signal to control anoperation of the VCO 430, and provides the generated signal to the VCO430. For example, the carrier phase converter 420 generates a controlsignal to turn on and off the VCO 430 per predetermined period, andprovides the generated control signal to the VCO 430. The RF oscillatingsignal is output from the VCO 430 in response to the control signal,which may have a phase randomly selected in a range of 0 degrees to 360degrees.

The power amplifier 460 generates an RF signal by inputting an RFoscillating signal with a phase randomly changed and a low frequencysignal, which is output from the pulse shaper 450, and wirelesslytransmits the generated RF signal.

FIG. 5 illustrates another example of an operation to transmit an RFsignal based on a method to convert a carrier phase, in accord with anillustrative configuration.

A transmitter 510 illustrated in FIG. 5 corresponds to the example ofthe transmitter 210 of FIG. 2. Accordingly, for any descriptions omittedin FIG. 5, reference may be made to FIG. 2.

Referring to FIG. 5, the transmitter 510 includes a data encoder 520, apulse shaper 530, a mixer 560, a VCO 540, a carrier phase converter 550,and a power amplifier 570.

The data encoder 520 encodes data to be transmitted in a form of atransmission bit. The data encoder 520 maps input data, or a datasequence, to a predetermined element set. The pulse shaper 530 generatesa pulse corresponding to data input based on a result of the mappingperformed at the data encoder 520. The pulse shaper 530 multiplies anoutput value of the data encoder 520 and a predetermined pulse shape,and generates a pulse corresponding to the data. The pulse shaper 530overlaps pulses corresponding to the data sequence on a time axis, andconverts the data sequence to a pulse series.

The VCO 540 generates an RF oscillating signal corresponding to acarrier frequency, and outputs the generated RF oscillating signal.

The carrier phase converter 550 randomly changes a phase of the RFoscillating signal output from the VCO 540. The carrier phase converter550 generates a random carrier phase, applies the generated carrierphase to an RF oscillating signal, and randomly changes the phase of theRF oscillating signal. The carrier phase converter 550 randomly changesthe phase of the RF oscillating signal by applying a function having apredetermined value, in a time interval determined based on atransmission period of a transmission symbol. Also, the carrier phaseconverter 550 changes the phase of the RF oscillating signal using aplurality of functions. The carrier phase converter 550 controls anoperation of an oscillator to output an RF oscillating signal, andchanges the phase of the RF oscillating signal to a continuous phasevalue.

The mixer 560 generates an RF signal corresponding to input data bymultiplying the RF oscillating signal, to which the random carrier phaseoutput by the carrier phase converter 550 is applied, and a pulse seriesof a low frequency band output from the pulse shaper 530. The generatedRF signal is transmitted to a receiver through the power amplifier 570.

FIG. 6 illustrates an example of a detailed configuration of a dataencoder 610, in accordance with an illustrative configuration.

When a system for wireless communication including a transmitter and areceiver uses an error correction encoding scheme and a spreading codesequence, the data encoder 230 of FIG. 2 may include the data encoder620 of FIG. 6. The data encoder 610 of FIG. 6 includes a channel encoder620 to perform encoding through an error correction code in the inputdata, a spreader 630 to apply a spreading code sequence to the encodedinput data, and a symbol mapping unit 640 to map a predetermined symbolwith the encoded input data to which a spreading code sequence isapplied.

FIG. 7 illustrates an example of an operation of a transmitter based ona signal waveform, in accord with an illustrative configuration.

A data encoder 710, a pulse shaper 720, a VCO 730, a carrier phaseconverter 740, and a power amplifier 750 of FIG. 7 may correspond tovarious configurations of FIG. 5. Therefore, for detailed descriptionsof operation of configurations of FIG. 7 omitted herein, reference maybe to FIG. 5.

The data encoder 710 of FIG. 7 is assumed to be a binary encoder toencode input data to a single element included in an element set {0, 1}.A shape of a pulse output from the pulse shaper 720, which may be adigital pulse shaping filter, may have a shape of a quantized Gaussianpulse. Pulse shaping may refer to adjusting a shape of a pulse, suchthat the shape of the pulse is not distorted in a limited bandwidth whena transmission waveform corresponding to a predetermined transmissionbit is transmitted because a frequency bandwidth of a wireless channelavailable is limited.

When an output of the data encoder 710 is [1 0 1 1 0 1], an outputsignal 760 from the pulse shaper 720 has a shape of overlapping pulsescorresponding to a plurality of outputs. The carrier phase converter 740randomly changes a phase of an RF oscillating signal 770 output from theVCO 730 to “0” degrees or 180 degrees. The carrier phase converter 740applies a function u(t) 780 to the RF oscillating signal 770 from theVCO 730. The function u(t) 780 represents a signal waveform that israndomly changed to +1 or −1 in a time interval. The carrier phaseconverter 740 is further configured to change a phase of the RFoscillating signal 770 to “0” or 180 degrees at points of time, whichcorrespond to positive integer multiples of a transmission symbolperiod. An RF oscillating signal 790 of which a phase is randomlyconverted may bear no relevance to the output of the data encoder 710.Also, information associated with the changed phase may not be sharedwith a receiver.

The carrier phase converter 740 changes the phase of the RF oscillatingsignal 770 per transmission symbol period T second, or per positiveinteger multiple of T second. When bit information corresponding to abinary number is encoded through the data encoder 710, a transmissionsymbol period T second corresponds to a single bit period. When the dataencoder 710 encodes data using a spreading code sequence, thetransmission symbol period T second corresponds to a single chip period.The output signal 760 of the pulse shaper 720 and the RF oscillatingsignal 790 of which the phase is randomly changed by the carrier phaseconverter 740 is multiplied and wirelessly transmitted via the poweramplifier 750.

A mathematical representation of an output signal v(t) of a VCO withrespect to a time “t” may be defined as Equation 1.

v(t)=√{square root over (2)}cos(2πf _(c) t)  [Equation 1]

In this example, f_(c) denotes a frequency, or a carrier frequency, ofan RF oscillating signal.

A mathematical representation of an output signal y(t) of the carrierphase converter 740 shown in FIG. 7 may be expressed as Equation 2.

$\begin{matrix}{{{y(t)} = {{{u(t)}{v(t)}} = {( {{u_{0}{{rect}( \frac{t}{T} )}} + {u_{1}{{rect}( \frac{t - T}{T} )}} + \ldots + {u_{N - 1}{{rect}( \frac{t - {( {N - 1} )T}}{T} )}}} ){v(t)}}}}\mspace{79mu} {where}\mspace{79mu} {u_{n} \in \{ {{- 1},1} \}}} & \lbrack {{Equation}\mspace{14mu} 2} \rbrack\end{matrix}$

In this example, v(t) denotes an output signal of the VCO 730, and u(t)denotes a function that is changed to +1 or −1 per transmission symbolperiod T. However, u(t) may change per positive integer multiple of thetransmission symbol period T. A “rect” function may be defined asEquation 3.

$\begin{matrix}{{{rect}(t)} = \{ \begin{matrix}{1,} & {{- 0.5} < t < 0.5} \\{0,} & {otherwise}\end{matrix} } & \lbrack {{Equation}\mspace{14mu} 3} \rbrack\end{matrix}$

An RF signal z(t) generated based on the output signal 760 of the pulseshaper 720 and the output signal of the carrier phase converter 740 maybe calculated according to Equation 4.

$\begin{matrix}\begin{matrix}{{z(t)} = {{p_{seq}(t)} \cdot {y(t)}}} \\{= {{{p_{seq}(t)} \cdot {u(t)} \cdot \sqrt{2}}{\cos ( {2\pi \; f_{c}t} )}}}\end{matrix} & \lbrack {{Equation}\mspace{14mu} 4} \rbrack\end{matrix}$

In this example, P_(seq)(t) denotes a time response function of anoverlapping pulse series, and may be represented as Equation 5.

$\begin{matrix}\begin{matrix}{{p_{seq}(t)} = {{c_{0}{p(t)}} + {c_{1}{p( {t - T} )}} + \ldots + {c_{N - 1}{p( {t - {( {N - 1} )T}} )}}}} \\{= {\sum\limits_{n = 0}^{N - 1}{c_{n}{p( {t - {nT}} )}}}}\end{matrix} & \lbrack {{Equation}\mspace{14mu} 5} \rbrack\end{matrix}$

In one example, p(t) denotes a time response function with respect to asingle pulse, and c_(n) denotes an output value of the data encoder 710output for a plurality of symbol periods. For example, when thetransmitter uses a noncoherent OOK modulation/demodulation scheme, theoutput value of the data encoder 710 has a value of “0” or “1”.

A low frequency band signal, or a baseband signal, obtained by excludinga high frequency band signal from an output signal of the poweramplifier 750 is represented in FIG. 13. FIG. 13 illustrates an exampleof equivalent baseband signal components of an output signal of a poweramplifier. In FIG. 13, a discontinuous quantized Gaussian pulse isapplied, and “0” and u(t) denote [c₀ c₁ c₂ c₃ c₄ c₅]=[1 0 1 1 0 1] and[u₀ u₁ u₂ u₃ u₄ u₅]=[+1 +1 −1 +1 −1 −1], respectively. A graph 1210illustrates a time response function P_(seq)(t) of an overlapping pulseseries, a graph 1220 illustrates a function u(t) changing pertransmission symbol period T second or per positive integer multiple ofT second, and a graph 1230 illustrates an equivalent baseband signalP_(seq,RCP)(t) included in an output signal of a power amplifier. Theequivalent baseband signal P_(seq,RCP)(t) may be represented asP_(seq)(t)·u(t).

FIG. 8 illustrates another example of an operation of a transmitterbased on a signal waveform, in accord with an illustrativeconfiguration.

A data encoder 810, a pulse shaper 820, a VCO 830, a carrier phaseconverter 840, and a power amplifier 860 illustrated in FIG. 8 maycorrespond to the plurality of configurations of FIG. 5. Therefore, forany detailed descriptions of operations pertaining to configurations inFIG. 8, reference may be made to FIG. 5. The carrier phase converter 840includes a phase shifter 850 for moving a phase of an RF oscillatingsignal 870. For example, the phase shifter 850 moves the phase of the RFoscillating signal 870 by −90 degrees. In FIG. 8, in one configuration,the phase shifter 850 moves the phase of the RF oscillating signal by−90 degrees.

The carrier phase converter 840 of FIG. 8 changes a phase of an RFoscillating signal to a predetermined value divided into an M number ofvalues, unlike the carrier phase converter 740 of FIG. 7. M=4 in FIG. 8,and a shape of a pulse output by the pulse shaper 820 is assumed tocorrespond to a quantized Gaussian pulse shape. An output signal fromthe pulse shaper 820 corresponds to a shape of overlapping pulsescorresponding to a plurality of outputs when an output of the dataencoder 810 is [1 0 1 1 0 1].

For example, the carrier phase converter 840 multiplies an RFoscillating signal output from a VCO and 1/√{square root over (2)},multiplies an RF oscillating signal of which a phase is moved by −90degrees and −1/√{square root over (2)} by the phase shifter 850, andadds results of the multiplications. A phase of a signal resulting fromthe addition may be changed to one of π/4, 3π/4, 5π/4, and 7π/4. Forinstance, when respective values of u_(I)(t) 880 and u_(Q)(t) 875 are1/√{square root over (2)} and −1/√{square root over (2)}, the phase ofthe RF oscillating signal 870 may be added by 7π/4. In one example, therespective values of u_(I)(t) 880 and u_(Q)(t) 875 refer to values thatchange the phase of the RF oscillating signal to an M number ofpredetermined differing values, and therefore, u_(I)(t) 880 and u_(Q)(t)875 may not necessarily be 1/√{square root over (2)} or −1/√{square rootover (2)}. The changed phase of the RF oscillating signal may bear norelevance to an output of the data encoder 810. A pulse signal outputfrom the pulse shaper 820 and the RF oscillating signal, with the phaserandomly changed at the carrier phase converter 840, may be multipliedand wirelessly transmitted via the power amplifier 860.

A mathematical representation of an output signal v(t) of the VCO 830with respect to a time “t” may be expressed as Equation 6.

v(t)=√{square root over (2)} cos(2πf _(c) t)  [Equation 6]

In one example, f_(c) denotes a frequency of the RF oscillating signal870.

A mathematic representation of an output signal y(t) of the carrierphase converter 840 of FIG. 8 may be simplified as Equation 7.

$\begin{matrix}{\mspace{79mu} {\begin{matrix}{{y(t)} = {{{{u_{I}(t)} \cdot \sqrt{2}}{\cos ( {2\pi \; f_{c}t} )}} - {{{u_{Q}(t)} \cdot \sqrt{2}}{\sin ( {2\pi \; f_{c}t} )}}}} \\{= {\sqrt{2}{\cos ( {{2\pi \; f_{c}t} + {\varphi (t)}} )}}}\end{matrix}\mspace{79mu} {where}{{{u_{I}(t)} = {{u_{I,0}{{rect}( \frac{t}{T} )}} + {u_{I,1}{{rect}( \frac{t - T}{T} )}} + \ldots + {u_{I,{N - 1}}{{rect}( \frac{t - {( {N - 1} )T}}{T} )}}}},{{u_{Q}(t)} = {{u_{Q,0}{{rect}( \frac{t}{T} )}} + {u_{Q,1}{{rect}( \frac{t - T}{T} )}} + \ldots + {u_{Q,{N - 1}}{{rect}( \frac{t - {( {N - 1} )T}}{T} )}}}},\mspace{79mu} {{\varphi (t)} = {\tan^{- 1}( \frac{u_{Q}(t)}{u_{I}(t)} )}},\mspace{79mu} {{{{and}\mspace{79mu} u_{I,n}^{2}} + u_{Q,n}^{2}} = {1\mspace{14mu} {for}\mspace{14mu} M\mspace{14mu} {elements}\mspace{14mu} {of}\mspace{14mu} ( {u_{I,n},u_{Q,n}} )}}}}} & \lbrack {{Equation}\mspace{14mu} 7} \rbrack\end{matrix}$

In one example, u_(I)(t) and u_(Q)(t) denote functions changing based ona relationship of u_(I)(t)²+u_(Q)(t)²=1 per transmission symbol periodT. However, u_(I)(t) and u_(Q)(t) may change per positive integermultiple of the transmission symbol period T.

An RF signal z(t) generated based on the output signal of the pulseshaper 820 and the output signal of the carrier phase converter 840 maybe represented as Equation 8.

$\begin{matrix}{\begin{matrix}{{z(t)} = {{p_{seq}(t)} \cdot {y(t)}}} \\{= {{p_{seq}(t)} \cdot ( {{{{u_{I}(t)} \cdot \sqrt{2}}{\cos ( {2\pi \; f_{c}t} )}} - {{{u_{Q}(t)} \cdot \sqrt{2}}{\sin ( {2\pi \; f_{c}t} )}}} )}} \\{= {{{p_{seq}(t)} \cdot \sqrt{2}}{\cos ( {{2\pi \; f_{c}t} + {\varphi (t)}} )}}}\end{matrix}\mspace{79mu} {where}\begin{matrix}{\mspace{79mu} {{p_{seq}(t)} = {{c_{0}{p(t)}} + {c_{1}{p( {t - T} )}} + \ldots + {c_{N - 1}{p( {t - {( {N - 1} )T}} )}}}}} \\{= {\sum\limits_{n = 0}^{N - 1}{c_{n}{p( {t - {nT}} )}}}}\end{matrix}} & \lbrack {{Equation}\mspace{14mu} 8} \rbrack\end{matrix}$

In one example, P_(seq)(t) denotes the time response function of theoverlapping pulse series of Equation 5, and p(t) denotes a time responsefunction with respect to a single pulse. c_(n), denotes an output valueof the data encoder 810 output for a plurality of symbol periods.

FIG. 9 illustrates still another example of an operation of atransmitter based on a signal waveform, in accord with an illustrativeexample.

A data encoder 910, a pulse shaper 920, a VCO 930, a carrier phaseconverter 940, and a power amplifier 950 illustrated in FIG. 9 maycorrespond to various configurations of FIG. 5. Therefore, for detaileddescriptions of operations pertaining to configurations of FIG. 9omitted herein, reference may be made to FIG. 5.

The carrier phase converter 940 of FIG. 9 controls an operation of theVCO 930, which is an oscillator to output an RF oscillating signal 970,and changes a phase of the RF oscillating signal 970, at random, to acontinuous phase value. The carrier phase converter 940 changes thephase of the RF oscillating signal 970 to a predetermined value in arange of “0” degree to 360 degrees. For example, the carrier phaseconverter 940 turns off and turns on the VCO 930 per predeterminedperiod, and randomly changes the phase of the RF oscillating signal 970to a continuous phase value in a range of “0” degree to 360 degrees.

As shown in FIGS. 7 and 8, a shape of a pulse output by the pulse shaper920 is assumed to be a quantized Gaussian pulse shape in FIG. 9. Anoutput signal 960 of the pulse shaper 920 may be in a shape ofoverlapping pulses corresponding to a plurality of outputs when anoutput of the data encoder 910 is [1 0 1 1 0 1].

A mathematical representation of an output signal v(t) of a VCO withrespect to a time “t” may be defined as Equation 9.

v(t)=√{square root over (2)}cos(2πf _(c) t)  [Equation 9]

In one example, f_(c) denotes a frequency of an RF oscillating signal.

A mathematical representation of an output signal y(t) of the carrierphase converter 940 of FIG. 9 may be defined as Equation 10.

$\begin{matrix}{\mspace{79mu} {{{y(t)} = {\sqrt{2}{\cos ( {{2\pi \; f_{c}t} + {\varphi (t)}} )}}}\mspace{79mu} {where}{{{\varphi (t)} = {{\varphi_{0}{{rect}( \frac{t}{T} )}} + {\varphi_{1}{{rect}( \frac{t - T}{T} )}} + \ldots + {\varphi_{N - 1}{{rect}( \frac{t - {( {N - 1} )T}}{T} )}}}},}}} & \lbrack {{Equation}\mspace{14mu} 10} \rbrack\end{matrix}$

-   -   and φ_(n) is a random variable over the interval [0, 2π]

In one example, a “rect” function may be represented as Equation 3. φ(t)denotes a continuous phase value in a range from “0” degree to 360degrees, for example, 2π. In Equation 10, φ(t) is assumed to change pertransmission symbol period T, however, φ(t) may change per positiveinteger multiple of T second.

The RF signal z(t) generated based on the output signal 960 of the pulseshaper 920 and the output signal of the carrier phase converter 940 maybe given by Equation 11.

$\begin{matrix}{{{z(t)} = {{{p_{seq}(t)} \cdot {y(t)}} = {{{p_{seq}(t)} \cdot \sqrt{2}}{\cos ( {{2\pi \; f_{c}t} + {\varphi (t)}} )}}}}{where}\begin{matrix}{{p_{seq}(t)} = {{c_{0}{p(t)}} + {c_{1}{p( {t - T} )}} + \ldots + {c_{N - 1}{p( {t - {( {N - 1} )T}} )}}}} \\{= {\sum\limits_{n = 0}^{N - 1}{c_{n}{p( {t - {nT}} )}}}}\end{matrix}} & \lbrack {{Equation}\mspace{14mu} 11} \rbrack\end{matrix}$

In one illustrative example, P_(seq)(t) denotes a time response functionof an overlapping pulse series, and may be simplified as Equation 5.p(t) denotes a time response function with respect to a single pulse,and c_(n) denotes an output value of a data encoder output for aplurality of symbol periods.

FIG. 10 illustrates an example of an operation to transmit an RF signalbased on a method to convert a baseband signal, in accord with anillustrative configuration.

Referring to FIG. 10, a transmitter may include a data encoder 1010, asignal converter 1020, a pulse shaper 1030, and an RF signal transmitter1050.

The data encoder 1010 encodes data to be transmitted in a form of atransmission bit. The data encoder 1010 maps input data, or a datasequence, to a predetermined element set, and outputs a quantizedresult. For example, the predetermined element set may be configured as“0” and predetermined positive numbers greater than “0”.

The signal converter 1020 randomly changes a code of the quantizedresult output from the data encoder 1010. For example, the signalconverter 1020 randomly changes a code of a quantized result to anegative value in a time interval determined based on a transmissionperiod of a transmission symbol. The signal converter 1020 applies afunction having a random value in the time interval determined based onthe transmission period of the transmission symbol to the quantizedresult, and changes the code of the quantized result. For example, thesignal converter 1020 multiplies a function, or a signal waveform u(t)1060, and the quantized result, and changes the code at random. u(t)1060 randomly changes per positive integer multiple of the transmissionsymbol period, and has a negative value. The function u(t) 1060 bears norelevance to an output of the data encoder 1010.

The signal converter 1020 randomly changes the code of the quantizedresult at points of time corresponding to a positive integer multiple ofthe transmission period of the transmission symbol. Also, the signalconverter 1020 changes the code of the quantized result and a size ofthe result. The signal converter 1020 adjusts a baseband signal outputfrom the data encoder 1010, and achieves an effect similar to an effectof adjusting a phase of an RF oscillating signal.

The pulse shaper 1030 converts an output signal of the signal converter1020 to a form of a pulse. The pulse shaper 1030 converts the quantizedresult of which the code is randomly changed to form the pulse. Thepulse shaper 1030 multiplies the output signal of the signal converter1020 and a predetermined pulse shape, and generates a pulsecorresponding to input data. The pulse shaper 1030 overlaps pulsescorresponding to a data sequence on a time axis, and converts the datasequence to a form of a series of pulses.

The RF signal transmission unit 1050 converts a pulse to an RF signal,based on an RF oscillating signal, and transmits the RF signal to areceiver. A VCO 1040 outputs an RF oscillating signal, and the RF signaltransmission unit 1050 multiplies the RF oscillating signal output fromthe VCO 1040 and a baseband signal output from the pulse shaper 1030,and generates an RF signal. The RF signal transmission unit 1050includes a power amplifier (not shown), and an RF signal is wirelesslytransmitted via a power amplifier.

FIG. 11 illustrates an example of an operation to transmit an RF signalbased on a method to convert a baseband signal, in accordance with anillustrative configuration.

A data encoder 1110, a signal converter 1120, at least two pulse shapers1130, a VCO 1140, and an RF signal transmission unit 1160 of FIG. 11correspond to the plurality of configurations of FIG. 10. Therefore, fordetailed descriptions of operations pertaining to configurations of FIG.11 omitted herein, reference may be made to FIG. 10. A phase shifter1150 moves a phase of an RF oscillating signal output from the VCO 1140.

The signal converter 1120 of FIG. 11 outputs to the pulse shaper 1130 aquantized result and a quantized result of which a code is changed atrandom. The signal converter 1120 randomly represents the code of thequantized result output from the data encoder 1110 ranging from apositive code to a negative code.

For example, the signal converter 1120 uses a function, for example,u_(I)(t) and u_(Q)(t), to output both, the quantized result and thequantized result of which the code is randomly changed. Values of (t)and u_(Q)(t) may have a positive value and a negative value, and maycorrespond to a value to adjust a phase of an RF oscillating frequencyto an M number of differing predetermined values. In this instance,irrespective of an output of the data encoder 1110, the values of (t)and u_(Q)(t) may be independent, and may change per transmission symbolperiod or per positive integer multiple of the transmission symbolperiod. Signals of u_(I)(t) and u_(Q)(t) are not be selected from agroup having a limited number of quantized components, and may have apredetermined continuous value. The signal converter 1120 adjusts avalue of u_(I)(t)²+u_(Q)(t)² to maintain a predetermined value, forexample, “1”.

FIG. 12 illustrates an example of an operation of a receiver 1210, inaccord with an illustrative example.

Referring to FIG. 12, an RF signal reception unit 1220 receives an RFsignal from a transmitter. The RF signal has a carrier phase which israndomly changed at the transmitter. For example, the RF signalcorresponds to an RF signal in which a carrier phase is randomlyreversed in a time interval determined based on a transmission period ofa transmission symbol. An envelope detector 1230 detects an envelopefrom the received RF signal. In this instance, in a process in which theenvelope detector 1230 detects an envelope, an irregular signal due to arandom carrier phase may disappear. An analog-to-digital converter (ADC)1240 performs sampling on the detected envelope, and converts anenvelope pattern, for example, from an analog pattern to a digitalsignal. A data decoder 1250 decodes data, based on the envelope of theRF signal. The data decoder 1250 extracts data using an envelope, andestimates a transmission symbol without using carrier phase informationof the RF signal. In a system for wireless communication including thetransmitter and the receiver 1210 using an error correction encodingscheme and a spreading code sequence, the data decoder 1250 of thereceiver 1210 includes a despreader 1260 and a channel decoder 1270. Thedespreader 1260 inversely performs an operation of the spreader 630 ofFIG. 6 to which a spreading code sequence is applied, and the channeldecoder 1270 decodes data in which an error correction code is includedperformed by the channel encoder 620 of FIG. 6.

FIG. 14 illustrates an example of a method of wireless communicationbetween a transmitter and a receiver based on signal waveform, in accordwith an illustrative configuration.

A signal 1410 represents a data sequence [0 1 1] to be input to thetransmitter. A signal 1420 is an output signal of a data encoder of thetransmitter, and represents a signal in which a spreading code sequenceis applied to a data sequence. When data input from the signal 1420 is“0”, a spreading code sequence [0 1 1 0] may be applied, and when theinput data is “1”, a spreading code sequence [1 0 0 1] may be applied.The signal 1430 is an output signal of a pulse shaper of thetransmitter, and represents a signal with a data sequence to which aspreading code sequence is applied is converted to a form of a pulse. Anoncoherent OOK scheme is a scheme in which a pulse is generated whendata from a signal 1430 is “1”, and a pulse is not generated when thedata is “0” is used. A signal 1440 is a signal used for a carrier phaseconverter of the transmitter to change a phase of an RF oscillatingsignal, and refers to a function having a random value. The signal 1440may have a random value of +1 or −1 per transmission symbol period orper positive integer multiple of the transmission symbol period. Asignal 1450 is an output signal of the carrier phase converter of thetransmitter, and refers to an RF oscillating signal in which the signal1440 is applied to the RF oscillating signal and a phase is changed. Asignal 1460 is an RF signal transmitted from the transmitter, and refersto an RF signal generated by the signal 1450 being applied to the signal1430. A signal 1470 is an output signal of an envelope detector of thereceiver, and refers to a signal as a result of detecting an envelopefrom an RF signal.

FIGS. 15 and 16 illustrate examples of a simulation result of comparingefficiency of an existing method of wireless communication andefficiency of a proposed method of wireless communication, in accordwith an illustrative configuration.

FIG. 15 illustrates a simulation result of estimating frequency powerdensity based on an assumption that an output value c_(n) of a dataencoder to be output for a plurality of symbol periods repeatedlyappears in a pattern of “1” and “0”, such as in c_(n)=[1, 0, 1, 0, 1, 0,. . . , 1, 0], and “N” corresponding to a length of c_(n) is 500.

A graph 1510 illustrates the frequency power density based on aconventional method of wireless communication in which a phase of an RFoscillating frequency is not randomly changed. A graph 1520 illustratesthe frequency power density when a phase of an RF oscillating frequencyis randomly changed per symbol transmission period T. A graph 1530illustrates the frequency power density when a phase of an RFoscillating frequency is randomly changed per 2T second, for example,two times greater than the symbol transmission period T.

The graph 1510 illustrating the simulation result, according to theconventional method, indicates that line spectrum in which power densityis concentrated in a predetermined frequency may occur when theconventional method is used. However, the graphs 1520 and 1530, in whicha phase of an RF oscillating frequency is randomly changed and estimatedbased on a symbol transmission period, indicate that the line spectrumis removed.

FIG. 16 illustrates a simulation result of frequency power densityestimated in an environment closer to reality than a simulationenvironment, in accord with an illustrative configuration.

A graph 1610 illustrates a frequency power density according to theconventional method of wireless communication in which a phase of an RFoscillating frequency is not randomly changed. A graph 1620 illustratesfrequency power density when a phase of an RF oscillating frequency israndomly changed per symbol transmission period T second. A detailedsimulation environment of FIG. 16 may be represented as Table 1.

TABLE 1 Notation RKQT Description f_(RBW) 100 KHz Resolution bandwidth T1 μs Symbol duration δ 0.0001 or 0.001  Sub-interval width of Tf forintegration (f: frequency) ρ 5 or 2 Interpolation factor for plotting r(r = 0, 1, . . . , R_(os)) R_(os)/2 Truncation factor for integrationInterval x_(shift) 0 Shift value of Tf for the lower limit of the firstintegration Ω 50 ohm Tx impedance α_(i) (l = 0, 1, . . . , L)sqrt(PA_out([11 9 Stepwise Gaussian 4 1]) ×10⁻³ × 50) filtercoefficients R_(os) 6 Tx oversampling rate N 320  Number of chip symbolsused for obtaining PSD c_(x) 1/0 alternating Tx chip symbol sequence[c_(· υ) c_(M)] [0, 1] Outside boundry chip values at both sides ofintegration interval

When the graph 1610, according to the conventional method, is comparedto the graph 1620 based on a scheme in which a phase of an RFoscillating frequency is randomly changed, power density in apredetermined frequency may be prevented by randomly changing the phaseof the RF oscillating frequency.

FIG. 17 illustrates an example of a method of wireless communicationperformed at a transmitter, in accord with an illustrativeconfiguration.

At operation 1710, the method at the transmitter converts input data toa form of a pulse. In other words, the method maps the input data to apredetermined element set, and converts the data to a discrete element.The method generates a pulse corresponding to the data input based on aresult of the mapping. The method generates a pulse corresponding to anelement, and outputs a pulse sequence represented by a plurality ofoverlapping pulses.

At operation 1720, the method at the transmitter randomly changes thephase of the RF oscillating signal. For instance, the method generates arandom carrier phase, applies the generated random carrier phase to theRF oscillating signal, and randomly changes the phase of the RFoscillating signal. The method applies a function, having a random valuein a time interval determined based on a transmission period of atransmission symbol, to an RF oscillating signal, and changes the phaseof the RF oscillating signal. The method changes the phase of the RFoscillating signal using a plurality of functions. The method determinesa change interval of a phase corresponding to a positive integermultiple of the transmission period of the transmission symbol, andrandomly changes the phase of the RF oscillating signal per determinedchange period.

At operation 1730, the method coverts a pulse to an RF signal, based onthe RF oscillating signal of which the phase is converted, and transmitsthe RF signal to the receiver. The method converts the pulse to the RFsignal, based on the RF oscillating signal of which the phase isconverted, and transmits the RF signal to the receiver.

FIG. 18 illustrates an example of a method of wireless communicationperformed at a transmitter, in accord with an illustrativeconfiguration.

At operation 1810, the method at the transmitter maps data to apredetermined element set, and outputs a quantized result. For example,the element set may be configured to be “0” and predetermined positivenumbers greater than “0”. The method encodes data to be transmitted in aform of a transmission bit.

At operation 1820, the method randomly changes a code of the quantizedresult. The method randomly changes the code of the result quantized ina time interval determined based on a transmission period of atransmission symbol to a negative code. The method applies a functionhaving a random value in the time interval determined based on thetransmission period of the transmission symbol to the quantized result,and changes the code of the quantized result. The method randomlychanges the code of the quantized result at points of time correspondingto a positive integer multiple of the transmission period of thetransmission symbol. Also, the method changes the code of the quantizedresult and a size of the result.

At operation 1830, the method converts the quantized result, of whichthe code is randomly changed, to a form of a pulse. The methodmultiplies the quantized result, of which the code is randomly changed,with a predetermined pulse shape, and generates a pulse corresponding toinput data. The method overlaps pulses corresponding to a data sequenceon a time axis, and converts the data sequence to the form of the pulse.

At operation 1840, the method converts a pulse based on the RFoscillating signal, and transmits the RF signal to a receiver. Themethod applies the pulse generated at operation 1830 to the RFoscillating signal output, and generates an RF signal. The methodwirelessly transmits the generated RF signal to the receiver.

FIG. 19 is a flowchart illustrating an example of a method of wirelesscommunication performed by a receiver, in accord with an illustrativeconfiguration.

At operation 1910, the method at the receiver receives an RF signal froma transmitter. The RF signal may have a carrier phase randomly changedat the transmitter. For example, the RF signal is an RF signal of whicha carrier phase is randomly reversed in a time interval determined basedon a transmission period of a transmission symbol, or an RF signal ofwhich a carrier phase is randomly changed to a predetermined value inthe time interval determined based on the transmission period of thetransmission symbol. Also, the RF signal may be an RF signal of which acarrier phase is randomly changed to a continuous phase value.

At operation 1920, the method detects an envelope of an RF signal. Anirregular signal by a random carrier phase may disappear during aprocess in which an envelope detector detects an envelope.

At operation 1930, the receiver may decode data, based on the envelopeof the RF signal. The method detects the envelope of the RF signal,samples on an envelope pattern, and converts an envelope pattern, forexample, an analog signal, to a digital signal. The method extractsdata, using the envelope, and estimates a transmission symbol withoutusing carrier phase information of the RF signal.

The units and apparatuses described herein may be implemented usinghardware components. The hardware components may include, for example,processors, controllers, transmitters, receivers, devices, and otherequivalent electronic components. The hardware components may beimplemented using one or more general-purpose or special purposecomputers, such as, for example, a processor, a controller and anarithmetic logic unit, a digital signal processor, a microcomputer, afield programmable array, a programmable logic unit, a microprocessor orany other device capable of responding to and executing instructions ina defined manner. The hardware components may run an operating system(OS) and one or more software applications that run on the OS. Thehardware components also may access, store, manipulate, process, andcreate data in response to execution of the software. For purpose ofsimplicity, the description of a processing device is used as singular;however, one skilled in the art will appreciated that a processingdevice may include multiple processing elements and multiple types ofprocessing elements. For example, a hardware component may includemultiple processors or a processor and a controller. In addition,different processing configurations are possible, such a parallelprocessors.

The processes, functions, methods and/or software described aboveincluding a method of wireless communication may be recorded, stored, orfixed in one or more non-transitory computer-readable storage media thatincludes program instructions to be implemented by a computer to cause aprocessor to execute or perform the program instructions. The media mayalso include, alone or in combination with the program instructions,data files, data structures, and the like. The media and programinstructions may be those specially designed and constructed, or theymay be of the kind well-known and available to those having skill in thecomputer software arts. Examples of non-transitory computer-readablemedia include magnetic media such as hard disks, floppy disks, andmagnetic tape; optical media such as CD ROM discs and DVDs;magneto-optical media such as optical discs; and hardware devices thatare specially configured to store and perform program instructions, suchas read-only memory (ROM), random access memory (RAM), flash memory, andthe like. Examples of program instructions include both machine code,such as produced by a compiler, and files containing higher level codethat may be executed by the computer using an interpreter. The describedhardware devices may be configured to act as one or more softwaremodules in order to perform the operations and methods described above,or vice versa. In addition, a non-transitory computer-readable storagemedium may be distributed among computer systems connected through anetwork and non-transitory computer-readable codes or programinstructions may be stored and executed in a decentralized manner.

A number of examples have been described above. Nevertheless, it shouldbe understood that various modifications may be made. For example,suitable results may be achieved if the described techniques areperformed in a different order and/or if components in a describedsystem, architecture, device, or circuit are combined in a differentmanner and/or replaced or supplemented by other components or theirequivalents. Accordingly, other implementations are within the scope ofthe following claims.

What is claimed is:
 1. A transmitter, comprising: a generator configuredto convert input data to a pulse; a converter configured to randomlychange a phase of a radio frequency (RF) oscillating signal; and atransmitter configured to convert the pulse to an RF signal based on theRF oscillating signal, and transmit the RF signal to a receiver.
 2. Thetransmitter of claim 1, wherein the converter is configured to randomlyreverse a phase of the RF oscillating signal in a time intervaldetermined based on a transmission period of a transmission symbol. 3.The transmitter of claim 1, wherein the converter is configured torandomly change a phase of the RF oscillating signal in a time intervaldetermined based on a transmission period of a transmission symbol to apredetermined value.
 4. The transmitter of claim 1, wherein theconverter is configured to control an operation of an oscillatoroutputting the RF oscillating signal, and change the phase of the RFoscillating signal to a continuous phase value.
 5. The transmitter ofclaim 1, wherein the converter is configured to apply a functionincluding a random value in a time interval, which is based on atransmission period of a transmission symbol, to the RF oscillatingsignal and change the phase of the RF oscillating signal.
 6. Thetransmitter of claim 1, wherein the converter is configured to determinechange periods of the phase corresponding to a positive integer multipleof a transmission period of a transmission symbol, and randomly changethe phase of the RF oscillating signal for the change periods.
 7. Thetransmitter of claim 1, wherein the transmitter is configured totransmit the RF signal to the receiver to decode data based on anenvelope of the received RF signal.
 8. The transmitter of claim 1,wherein the transmitter is configured to transmit the RF signal to thereceiver to decode data without using carrier phase information of theRF signal.
 9. The transmitter of claim 1, wherein the generatorcomprises: a data encoder configured to map input data to an elementset; and a pulse shaper configured to generate the pulse correspondingto the data based on a result of the mapping.
 10. The transmitter ofclaim 9, wherein the pulse shaper is configured to overlap pulsescorresponding to a data sequence on a time axis, convert the datasequence to a pulse series, and adjust a shape of each pulse to avoiddistortion of a transmission waveform in a limited bandwidth whiletransmitting the transmission waveform corresponding to a transmissionbit.
 11. A transmitter comprising: a data encoder configured to output aquantized result indicative of mapping input data to an element set; aconverter configured to randomly change a code of the quantized resultand output an output signal indicative thereof; a pulse shaperconfigured to convert the output signal to a form of a pulse; and atransmitter configured to convert the pulse to an RF signal based on anRF oscillating signal and transmit the RF signal to a receiver.
 12. Thetransmitter of claim 11, wherein the converter is configured to randomlychange the code to a negative code in a time interval determined basedon a transmission period of a transmission symbol.
 13. The transmitterof claim 11, wherein the converter is configured to apply a functionincluding a random value in a time interval, which is based on atransmission period of a transmission symbol, to the quantized resultand change the code and a size of the quantized result.
 14. Thetransmitter of claim 13, wherein the converter is configured to randomlychange the code of the quantized result at points of time correspondingto positive integer multiples of the transmission period.
 15. Thetransmitter of claim 13, wherein the data encoder comprises an encoderconfigured to perform encoding by including an error correction code inthe input data, a spreader configured to apply a spreading code sequenceto the encoded input data, and a symbol mapping unit configured to map asymbol with the encoded input data to which the spreading code sequenceis applied.
 16. The transmitter of claim 13, further comprising: a mixerconfigured to generate the RF signal corresponding to the input data bymultiplying the RF oscillating signal and a pulse series of a lowfrequency band.
 17. A receiver comprising: an envelope detectorconfigured to detect an envelope of a radio frequency (RF) signal; and adata decoder configured to decode data based on the envelope of the RFsignal, wherein the RF signal comprises a randomly changed carrierphase.
 18. The receiver of claim 17, wherein the RF signal is configuredto correspond to one of an RF signal with a carrier phase randomlyreversed in a time interval determined based on a transmission period ofa transmission symbol, an RF signal with a carrier phase randomlychanged to a predetermined value in a time interval determined based ona transmission period of a transmission symbol, and an RF signal with acarrier phase randomly changed to a continuous phase value.
 19. A methodof wireless communication at a transmitter, comprising: converting inputdata to a pulse; randomly changing a phase of a radio frequency (RF)oscillating signal; converting the pulse to an RF signal based on an RFoscillating signal; and transmitting the RF signal to a receiver.
 20. Amethod of wireless communication, comprising: receiving a radiofrequency (RF) signal from a transmitter; detecting an envelope of theRF signal; and decoding data based on the envelope of the RF signal,wherein the RF signal comprises a randomly changed carrier phase.